The present invention relates to cruise control systems and in particular to cruise control systems which include a distance sensor by which the system may monitor vehicles travelling in front of the equipped vehicle and adjust the speed of the equipped vehicle to maintain a set time based distance with a vehicle in front of the equipped vehicle.
With cruise control systems of this type in a cruise mode, the cruise control system will maintain the speed of the vehicle at that set by the driver. If however the distance sensor detects a slower moving vehicle in front of the equipped vehicle, the cruise control system will go into follow mode and will adjust the speed of the equipped vehicle to maintain a set time based distance or headway, to the vehicle ahead.
With such systems, problems are encountered when either the equipped vehicle and/or the vehicle in front of the equipped vehicle performs steering manoeuvres. For example, when vehicles enter a corner, because of the limited width of the field of view of the distance sensor, the distance sensor may lose the target vehicle in front of the equipped vehicle, at which time the cruise control system will go back to cruise mode and accelerate the vehicle at a pre-defined rate to reattain the set cruising speed. Such acceleration in a corner may be disconcerting to the driver of the equipped vehicle and may bring the equipped vehicle uncomfortably close to the target vehicle.
When however the equipped vehicle pulls out to overtake the target vehicle, it is desirable that the equipped vehicle resumes the cruise mode so that it will accelerate passed the target vehicle. If however the target vehicle pulls out into a faster lane of a multi-lane highway, if the equipped vehicle were to resume the cruise mode, then this may cause the equipped vehicle to overtake the target vehicle on the inside which may again be disconcerting to the driver of the equipped vehicle.
In accordance with one aspect of the present invention, a cruise control system for a motor vehicle comprises means for monitoring a target vehicle moving in front of the equipped vehicle, means for monitoring the speed of the equipped vehicle and means for monitoring steering manoeuvres of the equipped vehicle, the cruise control system controlling the throttle and/or brake systems of the vehicle to control the speed of the vehicle, the cruise control system being switchable between; a cruise mode in which it will maintain a set cruising speed when the path in front of the vehicle is clear and a follow mode in which it will maintain a preset headway with a target vehicle in front of the equipped vehicle; the system being switched from the cruise mode to the follow mode when the target vehicle moves inside the preset headway; the system switching from the follow mode to the cruise mode when the target vehicle is lost or moves outside the preset headway, the cruise control system applying a resume acceleration to accelerate the equipped vehicle back to the set cruising speed, the resume acceleration rate being adjusted as a function of steering manoeuvres carried out by the equipped vehicle.